1. Field of the Invention
The present invention relates to a solid polymer fuel cell and particularly, to a solid polymer fuel cell including an electrolyte membrane having a polymer ion-exchange component, and an air electrode and a fuel electrode between which the electrolyte membrane is sandwiched.
2. Description of the Related Art
There are conventionally known air and fuel electrodes, each of which is formed of a polymer ion-exchange component adapted to provide a proton conductivity to the air and fuel electrodes and functioning as a binder, catalyst particles comprising a catalyst metal carried on surfaces of carbon black particles, and polytetrafluoroethylene (PTFE) particles. The PTFE particles have a water-repellent property and function to adjust the water retention of each of the air electrodes and the fuel electrodes.
However, the use of the PTFE particles as a component for forming each of the air electrode and the fuel electrode is an obstacle for satisfying a requirement that the thickness of each of the air electrode and the fuel electrode is reduced to enhance the proton conductivity and to suppress the resistance over-voltage to a low level in order to provide a further enhancement in power-generating performance.
Such type of fuel cell employs a means of supplying air and hydrogen to the air electrode and the fuel electrode respectively after a moistening treatment in order to maintain the electrolyte membrane in a wet state and to ensure the proton conductivity of the electrolyte membrane. For this reason, the mounting of a moistener to an air supply line and a hydrogen supply line, an air-tight and water-tight sealing operation in the mounting of the moistener and the like are required. If a portion or all of the above-described means could be omitted, it would be effective for reducing the equipment cost and simplifying the structure.